The invention relates to an apparatus for melting metals in a vacuum chamber with a weir box disposed therein, an electron beam generator disposed above the weir box, and a crucible for withdrawing the molten metal flowing out from the weir box.
It has long been a problem in electron beam technology, when recycling titanium, to dissolve the titanium nitrite which it contains. There are calculations according to which titanium nitrite would have to be in the melt for approximately 1000 seconds before it would be dissolved. This means that the weir box required would have to assume extremely large dimensions, which would have a negative effect on the energy balance. The use of such a large weir box is not a practical solution.
In electron beam melting furnaces it is furthermore known, for the improvement and further development of nickel-base alloys, to provide the weir box for receiving the melt with a mechanical weir in the form of a water-cooled copper strip. Such weirs have been placed on the upper, parallel marginal portions of the weir box, the bottom edge of the mechanical weir held across the flow of the melt being slightly immersed in the melt and thus holding back the floating impurities collecting on the surface of the melt, i.e., prevents them from passing over the spout into the offtake means or crucible. The nonmetallic inclusions in the melt can be eliminated additionally by means of an electrothermal barrier, an electron beam stripe running across the width of the trough ahead of the outlet spout.
The present invention sets for itself the task of creating an apparatus of the kind described above which will be especially adapted for dissolving rapidly and completely the titanium nitrite generally present in a titanium melt. At the same time the apparatus is to be made as compact and reliable in operation as possible.